For the past couple of days my rabbit hasn't used his litter box, I've checked it everyday and its dry. He's peed on my bed and it seems more than the usual amount. Hes being quite aggressive and some times when i walk pas him he will 'growl' and jump towards me. I took him to the vets yesterday and they checked him over and nothing is wrong with him, hes eating and drinking normally. Has anyone had anything like this before?